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Penetrationsberechnung
Penetration Mechanics left|{name}|link= Aiming properly and hitting the enemy tank are only the means to an end, and that is actually damaging and eventually disabling it. And that is not automatic. Once you have hit an enemy vehicle, the game then calculates where the shot hit the enemy, at what angle you struck the armour, the effective thickness of the armour (based on the impact angle), and thus ultimately whether your shell penetrates the armour. Impact Angle The angle at which an Armour Piercing (AP) or Armour Piercing Composite Rigid (APCR) shell hits the target's armour is crucial for penetrating it. The ideal impact angle is along the normal, i.e. perpendicular to the armour plate. The actual impact angle is calculated as the deviation from the normal. For this, the ballistic flight path of the shell is taken into account, which can be particularly important for artillery guns and their high arcing trajectories if you fire AP or HEAT shells with them. If the shell hits an external module (e.g. tracks, observation device, turret rotator), impact angle is not taken into account. The exception to this rule is the gun. Impact angle is also not taken into account for High-Explosive (HE) shells, because those explode on impact. Shell Normalization The impact angle of AP and APCR shells onto a vehicles armour is normalized, i.e. adjusted towards the armour's normal axis at the point of impact. In case of spaced armour, shells are normalized twice at the point of impact on the spaced armour, and if they penetrate, continue on their way into the vehicle. No additional normalization occurs when the shell hits the hull armour after penetrating the spaced armour. If a shell penetrates spaced armour, it continues along its normalized flight path into the vehicle. Once it impacts the hull armour, the remaining penetration potential (i.e. the original penetration potential minus the effective armour thickness of the spaced armour) is used to calculate whether the shell penetrates the hull proper. We are told the AP and APCR shells are currently normalized between 4° and 5°. The normalization amount is a constant value depending on the shell, there is no randomizaton. The impact angle of HEAT shells is currently not normalized at all. Ricochet If the normalized impact angle of an AP, APCR or HEAT shell on the target's armour exceeds 70°, a ricochet (also called a bounce) occurs and the shell is deflected off the target without causing any damage. A ricochet can also occur on the hull armour after penetrating spaced armour. As mentioned above, impact angle is not taken into account when hitting external modules except the gun, so a ricochet off those is impossible. A ricochet off terrain features, buildings or wrecks is impossible. Overmatch If the shell's caliber is over 3 times greater than the nominal thickness of the armour, shell normalization is increased by that factor. For example, hitting 20mm of armour with a 120mm shell, your caliber overmatches the armour by a factor of six, so your shell is normalized six times more than it would be by default. Given a minimum normalization amount of 8° for AP and APCR shells, in cases of overmatch your impact angle is effectively normalized by at least 24°. Since the actual impact angle cannot exceed 90°, in case of overmatch the normalized impact angle cannot be greater than 66°. That means that a ricochet at the point of impact becomes impossible. Note that if you impact spaced armour first, even if you penetrate that your shell may still ricochet off the underlying hull armour. Naturally, in cases where no shell normalization occurs (HE and HEAT shells or external module hits), overmatch plays no role. Effective Armour Thickness Your tank is armoured with plates of varying thicknesses. The game only provides you with the nominal armour strength of the three main armour plates of your tank's hull and turret, respectively. However, the tanks are actually modelled in much greater detail. The penetration indicator can help you discover the actual nominal armour thickness of your target. However, the nomimal thickness of an armour plate is just the minimal amount of armour a shell impacting it must penetrate. As soon as the impact angle deviates from the normal, i.e. is not perfectly perpendicular to the armour plate's surface, the effective armour thickness that the shell needs to penetrate will be higher than the nominal armour thickness: link= The effective armour thickness is calculated by dividing the nominal armour thickness with the cosine of the nominal impact angle. For example, in the diagram above we have a nominal armour thickness of 100mm and an impact angle of 30°, thus we have an effective armour thickness of 100mm/cos(30°) = 115.47mm that the shell needs to be able to penetrate. In other words, at an impact angle of 30° the armour is effectively over 115.47% stronger than its nominal value. The following table provides the coefficients for a number of normalized impact angles: Impact Angle Effective Armour Thickness 0° 100% 10° 101.54% 20° 106.42% 30° 115.47% 40° 130.54% 50° 155.57% 60° 200% 70° 292.38% > 70° Ricochet As you can see, the effective armour thickness increases expontentially with the impact angle. For shells impacting you at 60° your armour is effectively twice as thick and at 70° nearly three times as thick. As explained above, for angles higher than 70° all shells will ricochet regardless of armour thickness. The same applies to your targets, of course, so always take that into account when deciding if and where to shoot them. Reducing the impact angle to your target only slightly will exponentially reduce its effective armour thickness and a target that was previously impossible for you to penetrate may suddenly become easy prey. This is also the reason why you should always attack from two different angles at once. A target can only maximize their effective armour in one direction, as soon as they try to accomodate two possible impact angles they suffer an exponential loss in effective armour thickness towards both of them (thus if you are the one getting flanked while in a strongly armoured tank it is best to maximize your effective armour towards one opponent while shooting the other one). Armour Homogenization Factor Unfortunately, in addition to the above the game also uses a hidden armour strength modifier called the armour homogenization factor. This is set individually for each tank and last known values date from closed beta, where this hidden factor would affect effective armour strengths between 100% and 120%. Armour homogenziation is used for all hull/turret armour but not for armour values of modules and crew (which of course are hidden from the players as well, so this is only a small consolation). Penetration Randomization Penetration values displayed for a gun/shell combination are average values. The actual penetration value is randomized by up to +/- 25% around the average value. Randomization occurs on impact with the target, separately for each new shell you fire. Penetration Loss over Distance Since shell speed decreases the longer a shell flies, the game models linear penetration loss over distance depending on the gun and shell type used: * Armour Piercing (AP) shells experience low penetration loss over distance. * Armour Piercing Composite Rigid (APCR) shells generally experience high penetration loss over distance (the exception are the APCR shells used by tier 10 mediums) * High-Explosive (HE) and High-Explosive Anti-Tank shells (HEAT) shells experience no penetration loss at all. The penetration values displayed in game indicate average penetration values at 0-100m distance (no penetration loss occurs within this range). Penetration values at higher distances are not displayed. As a rule of thumb, the higher the tier of the gun used, the lower the penetration loss over distance. For example, a Leichttraktor loses up to 17.5% penetration firing AP shells and 51.4% firing APCR shells with its default gun, whereas a Maus only loses about 2% with AP and 15.4% with APCR. Dud Rounds There also appears to be a small chance for any round to bounce no matter what other factors are involved. There have been observed instances of shells impacting non-spaced armour flat on or fully normalized and failing to penetrate even when the average penetration value is several times the armour thickness such as 175mm average penetration failing to penetrate 30mm of armor. Even with -25% penetration randomization and other factors calculated for it would be mathematically impossible for such a round, that hits, to fail to penetrate non-spaced armour at observable ranges. Double Penetration A shell can continue its flight path after the initial impact, either on the outside of the tank in case of ricochet or inside of the tank following penetration of spaced armour, hull armour or external modules. The remaining penetration potential is the initial penetration value, randomized at the point of impact +/- 25%, minus whatever effective armour thickness that was penetrated. This remaining penetration potential is then used to calculate whether any other armour plates that are hit can be penetrated. Internal modules or crew members have no armour and thus will always get hit if any penetration potential is left in the shell. Note that the penetration model is simplified and after initially impacting a vehicle a shell is "bound" to this vehicle and cannot hit any other tank anymore. That means that a shell can neither ricochet off a tank to hit another tank within its deflected flight path, nor can a shell pass through a tank to hit another tank behind it. A shell's flight path also ends after impacting the ground or buildings.